Fundamental transport properties in N-phenyl thin films

Conductivity of N-phenyl (N = 3, 4) thin films (with thickness 2-15 mum) was investigated experimentally and theoretically using molecular dynamics simulations of microcrystallite (MC) occurrence and quantum chemical band structure calculations. At the first time, process of carrier kinetics is considered within a framework of self-consistent band structure approach. The external electric field was varied up to 10(6) V cm(-1) using Al-Au electrodes with different voltage polarities. Depending on the film thickness and N, we have discovered the appearance of minima of effective activation energy. The observed effects are explained as a competition between the diffusion recombination of carriers from the trapping MC levels and the potential gradients on the MC surfaces. A good agreement between the performed theoretical simulations and experimental data is achieved.